Simultaneous Determination of 10 Adulterants in Antihypertensive Functional Foods Using Multi-Walled Carbon Nanotubes-Dispersive Solid-Phase Extraction Coupled with High Performance Liquid Chromatography.

Consumption of functional foods based on extracts from selected herbs to alleviate hypertension is an increasingly common practice in China. Adulteration of these foods with pharmaceuticals can significantly impact a consumer's health. To control the quality of the functional foods effectively, a method for the simultaneous determination of 10 common adulterants including chlortalidone, hydrochlorothiazide, indapamide, metoprolol, nifedipine, nimodipine, nitrendipine, reserpine, triamterene and valsartan in antihypertensive functional foods was developed. The target chemicals in samples were ultrasonically extracted with acetonitrile, and then cleaned-up with multi-walled carbon natotubes-dispersive solid-phase extraction. Finally, the analytes were separated with a C18 column using binary mobile phases consisting of acetonitrile and 0.03 mol/L KH2PO4 solutions (pH 3.0). The flow rate of the mobile phase was 0.80 mL/min, and the column temperature was 35°C. The detection wavelength was set at 220 nm. The limits of detection and quantification of the method ranged from 0.014 to 0.053 and 0.047 to 0.178 μg/mL, respectively. The recoveries of the method were in the range of 80.1-98.1% with relative standard deviations <9.53%. The method was successfully applied to the determination of the target chemicals in real samples and simulated samples, and respirine was detected in one tonic wine sample with a concentration of 56.8 ± 1.2 mg/L.